Belt-type presses for making particleboard, fiberboard, copper clad boards for printed circuit boards and the like are known in the prior art related to the invention. The materials being pressed (known as press materials or press products) can include laminates, rubber products, particleboard, plastics and any other products formed by pressing multiple layers together. Generally, belt presses comprise an endless upper press belt, often a steel press belt, circulated over spaced-apart guide belt rollers, and a corresponding endless lower press belt, also often a steel press belt, circulated over spaced-apart guide belt rollers as well. Between them, these press belts form a pressing gap or pressing region of the belt-type press, between the press framework having upper and lower platens. The upper and lower belts each have their own drive mechanisms. In a known press of this type, two chains are associated with each of the press platens and press belts, or a total of four chains per belt press system. The upper and lower platens form an entrance region along a complete horizontal plane.
Into the pressing region between the platens and their corresponding press belts, the spaced apart rollers are fed and guided along a circulation path with the aid of upper and lower roller circulation mechanisms. The roller circulation mechanisms comprise upper and lower chain sets, where each set is driven by a chain drive sprocket. The chain sets, in turn, circulate or drive the rollers so that the rollers move along with the press belts, situated between their respective belts and the platens. Guide rails are used to channel the movement of the chain sets and rollers in the intended direction. Thus, the upper press mechanism has two chains with rollers disposed across the width of the press between both chains, and the lower press mechanism has two corresponding chains with rollers disposed between them as well.
In many cases, the upper and lower platens are heated. The rollers are situated between the steel press belts and the heated platens. The rollers are equally spaced apart and roll more or less along with the belt. As press material is inserted into the entrance of the pressing region (or press gap entrance), the steel press belts are contacted by the press products on one side and the rollers on the other. In turn, the rollers contact the press belts and the heated platens, thus acting to transfer heat from the platens to the steel belts. The heat is ultimately transferred from the platen to the steel press belt via the rollers. Finally, the heat is transferred from the steel press belt to the press material.
For the circulation of rolling rods to the press gap entrance, the rolling rods are channeled along guide rails and links cooperating with sliding wheels and guide wheels. Both sets of chains, that is, the upper and lower chain sets, are driven individually by chain drive motors. Each motor is connected to a chain drive axis, which has chain drive sprockets disposed at its ends. The upper and lower chain drive systems, however, are not connected mechanically because the belt press is specifically designed to open. That is, the upper and lower belt press mechanisms form a "C", with the upper belt press as the top half of the "C", and the lower belt press as the bottom half. In this manner, the belt press system can easily be maintained, and all moving parts are freely accessible to the operator or maintenance personnel.
During the manufacture of complex multilayer press products, the upper and lower press belts are in constant contact with a multiplicity of various materials. When single side clad composite materials are made, the unclad side must be coated with a release film or chemical, so that it will not adhere to the press belt. The clad side may or may not require a release agent. For example, if laminates for electronic circuit boards are being fabricated, copper cladding may be required on one or both sides of the laminate (or not at all). A release agent may then be used to prevent an unclad surface from sticking to a pressing surface, such as a press belt. In this application, the clad side would not normally require a release agent. Because various materials are being pressed at different times, it has been a problem in the art to insure the purity of the materials being applied to the press belts at any given instant in time. This problem stems from the fact that cleaning the press belts between the applications of different chemicals can be time consuming, and at times virtually impossible.
The problem is prevalent in any manufacturing process where the pressed material or laminates have several diverse layers. For example, one layer deposited may entail using certain chemicals not compatible with those used for depositing other subsequent layers. In such a case, the diverse chemicals may react adversely. In order to prevent impurities (which could render subsequent coatings useless), it is necessary to completely clean off the press belts between steps involving the application of different liquids. However, it is very time consuming to clean the press belts, and a need exists for effective and efficient belt cleaning.
Many problems also result from trying to uniformly apply liquids to press belts. Because the belts (often made of steel) are substantially rigid, it is necessary to have an applicator (and cleaner) roller capable of uniformly contacting the steel belt at all times. In this manner, a uniform layer of laminating material can be applied to the object being pressed, and in the context of cleaning, the belt can be completely scraped clean. If a residue of previous, incompatible chemicals (contaminates) are left on the belt, defects or impurities in the press products can result. Also, when applying liquids to the press belt, it may be necessary to adjust the temperature (often to cool it off) of the liquid being applied.
Other problems result from conventional applicators. Because the belts are to some degree porous, the fluids need to be worked into the belts. Also, combustible fluids are often used, and proper ventilation is very important. In addition, because applicator rollers themselves become contaminated with the various fluids, there exists a need in the art to have a mechanism that cleans not only the press belt but the applicator rollers themselves, and to be able to clean the applicator rollers even if the applicator rollers are disengaged from their press belts. If not, the contaminates would merely be transported back and forth between the press belt and the applicator roller.